The present invention relates to a polymerizable composition, comprising as a component A, at least one organosilicon compound containing at least two ≡Si—H groups that are reactive in the hydrosilylation reaction and as a component B, a benzoxazine compound containing at least two unsaturated carbon-carbon bonds that are reactive in the hydrosilylation reaction with component A. Further subject matters of the present invention are adhesives, sealants or coatings that comprise the polymerizable composition according to the invention, as well as the polymerization products of said compositions.
Epoxy-based resin systems have been successfully used for a long time in the aeronautical, automotive or electronics industries as adhesives, sealants or for coating surfaces or employed as resin systems with a range of different materials for manufacturing composites.
Benzoxazine-based resin systems generally exhibit a high glass transition temperature and are characterized by their good electrical properties and their positive flame retardant behavior.
Mixtures of epoxy resins and benzoxazine resins are described for example in U.S. Pat. Nos. 4,607,091, 5,021,484 and 5,200,452. The mixtures of the cited resin systems are characterized by their advantageous processability because the epoxy resin decisively reduces the viscosity of the composition. The cited resin systems can be employed in the electronic industry due to inter alia the favorable processability even with high filler contents.
Ternary mixtures of epoxy resins, benzoxazine resins and phenol resins are likewise known. Mixtures of this type are described for example in U.S. Pat. No. 6,207,786.
In addition, mixtures of benzoxazines with materials other than epoxy resins or phenol resins are known. Thus, U.S. Pat. No. 6,620,925 discloses a curable composition, comprising certain benzoxazines and additional curable compounds, for example selected from vinyl ethers, vinylsilanes or from compounds that contain an allyl or vinyl group.
Polymers are likewise known that, in addition to benzoxazine moieties, contain at least one further structural moiety that differs from the first mentioned. Thus, Japanese patent application JP-A-2007-154018 claims benzoxazine-based resin systems that can be manufactured by treating methyl-substituted hexamethylene-diamines with formaldehyde and diphenols. Benzoxazine-based resin systems, manufactured using araliphatic diamines, are known from JP-A 2007-106.
Japanese patent application JP-A-2007-146070 relates to benzoxazine-based resin systems that are manufactured by treating various polysiloxane diamines with formaldehyde and diphenols. The resulting polymers are notably characterized by their good dielectric and mechanical properties.
Silsesquioxane-containing benzoxazine compounds are described by F. C. Chang et al. in “Syntheses, thermal properties, and phase morphologies of novel benzoxazines functionalized with polyhedral oligomeric silsesquioxane (POSS) nanocomposites” Polymer, Elsevier Science Publishers B.V, GB, vol. 45, No. 18, 6321-6331 (2004).
The siloxane group-containing benzoxazine-based resin systems described in the prior art can be thermally polymerized by a self-initiating mechanism or by adding cationic initiators. A later post-crosslinking that is frequently desired in industry, in particular a radical post-crosslinking of the resulting polymers, in order to increase the final strength, is generally not possible. Such a later post-crosslinking is desirable, for example with adhesives, coating agents or sealants.